The compositions comprise a single or a blend of saccharide siloxane copolymers that is cross-linked in the presence of reactive cross-linking agents. A preferred saccharide siloxane composition for use in the present invention is a saccharide-derived polyhydroxyl-functional moiety covalently linked to an organosilicon backbone. The cross-linking is achieved by reacting suitable reactive cross-linkers to the copolymers via the polyhydroxy-functionality of the saccharide components.
These film-forming compositions can be used to form a cohesive and substantive films on human or animal biological tissues. The resulting film is designed to deliver actives to the adhering substrate and to the underlying layers. It can also be a protective and barrier film for the covered area, and be used to modify the hydration of the underlying tissues. It can also provide an aesthetic and cosmetic aspect to the covered surface. Thus, it has utility in topical administration, wound care and skin care applications. The invention further relates to the film forming compositions, cured films, and articles of manufacture comprised thereof.
Many formulations for forming films are known in the cosmetic, medical and pharmaceutical art. These include, for example, ointments, salves, creams, lotions, gels, elastomers and the like. Some of these formulations use silicone-based materials as key components. Silicone based materials are desirable in these formulations since they are generally inert to the body. These products are designed to provide a variety of benefits, for example, moisturize dry skin, mask surface imperfections, allow effective delivery of actives while being cosmetically acceptable during and after application onto various skin areas of the body.
Well-known formulations are based on blends of silicone fluids and are broadly used in cosmetic skin care. They combine various viscosities of silicone fluids from volatiles to gum type materials as described in U.S. Pat. No. 6,325,990. Other formulations contain cross-linked organosiloxanes swollen in low molecular weight silicone fluids, and are referred to as elastomer blends as described in U.S. Pat. Nos. 5,654,362 and 6,221,979, and in European Publication Nos: EP848029, EP869142, EP934959, EP1020494, and EP1057872. These compositions show interesting film forming property by spreading easily to various surfaces but their substantivity is low due to an intrinsic cohesion weakness.
Similar compositions, as described for example in WO 97/17057, WO 97/17058, and WO 97/17059, are obtained by blending silicate resins, such as those described in U.S. Pat. Nos. 3,936,582, 2,676,182, 2,857,356 and 2,676,182, with silicone fluids. These compositions show interesting film forming property by spreading easily to various surfaces but their substantivity is limited due to lack of condensation between the resin and the polymeric fluid.
The silicate resin and the silicone fluid can be condensed together according to Canadian Application No. 711,756. The resulting material most likely has adhesive pressure sensitive properties as described in Handbook of Pressure Sensitive Adhesive Technology, 3rd edition by Donatas Satas, Satas & Associates, Warwick, R.I. 1989 (ISBN #0963799339), and EP 0180377. These compositions show interesting film forming properties as well as high substantivity and basically demonstrate no tack (essentially, resistance to separation, or, generally, “stickiness”) property at high resin content (defined as greater than about 65 weight percent); however because of their intrinsic visco-elastic property they remain sensitive to plasticizing effects and may become tackier by absorbing plasticizing species.
Another example of silicon-based materials in known film forming formulations is provided in European Publication 465,744. This publication teaches the use of a multi-part formulation including an active agent, a Si—H containing polymer, a polymer having unsaturated groups bound to silicon, a catalyst and a hydrophilic component. The formulation is mixed and applied to the body where it cures and forms a controlled release gel. This cross-linkable and elastomeric composition allows for significant reduction of sensitivity to plasticizing effect. The prior art methods such as those described in EP 465,744, however, have several disadvantages. For instance, in such methods the person utilizing the formulation must be skilled so as to ensure adequate mixing of the appropriate amounts of component materials in the formulation. Special care must be exercised to apply the correct amount of the mixed formulation to the desired site before it gels. Similarly, such a method can be an inconvenient and messy for the end user. Similar systems are described in the following publications U.S. Pat. No. 6,471,985, EP 0 506 241, EP 0 865 787, and WO 2004/108175.
Another patent document, WO 90/03809, teaches a coating material for forming bandages comprising a siloxane-containing bandage material diluted in a volatile polydimethylsiloxane. These coatings are distinguishable from the films described and claimed herein. Similar systems are described in the following publications EP 0438496, EP0572416, however these patents describe polymers with acrylate backbones and pendant siloxane functionality.
GB 2407496 and WO 01/96450 teach a method for forming a film on a biological surface. The method comprises mixing an alkylene trialkoxysilyl-terminated polysiloxane; an alkoxysilane; a titanate catalyst; a filler; and a volatile diluent to form a formulation. The formulation is then applied onto a biological surface where it cures in situ on the surface to form a film. This film-former suffers from the characteristic that it cures upon contact with moisture, making it very sensitive to humidity and impacting its stability if it is not properly packaged.
Other known options include solutions of nitrocellulose-silicone blends or silicone-polyamide compositions. While the methods described above may allow for delivering certain important properties, none of them have demonstrated the capability to deliver all important properties in a single embodiment.
Organosiloxane-based elastomers formed from crosslinking organosiloxane polymers are well known in the art and such materials have wide-ranging utility as coatings which confer desirable surface properties to the coated substrate. Such properties include, for example, enhanced resistance to wear, thermal stability, hydrophobicity and resistance to water, adhesion control and release, frictional control including anti-slip capability, and the like. Various fillers and other additives may be included within the elastomeric matrix to provide coatings with even more varied performance benefits. The mechanical, chemical and ionic characteristics of the crosslinked network matrix influences both the nature and amount of additives that may suitably be included.
Compositions and cured coating compositions comprising crosslinked carbohydrates are known in the art. However, the present inventors are unaware of film-forming compositions comprising saccharide-siloxane copolymers crosslinked via the polyhydroxyl functionality of the saccharide. The networked matrix and cured films formed from these unique crosslinkable compositions provide a blended property profile comprising attributes of both silicone and carbohydrate-based matrices which may support, retain and/or controllably release a variety of additives. Crosslinking via the saccharide component of the copolymer yields elastomers possessing a property profile making them desirable for particular applications.
There is a need in the art for film-forming compositions capable of delivering actives to and through biological substrates. The cured films comprised therefrom, which reflect the benefits and characteristics known to be imparted by films that comprise both silicone and carbohydrate components.